my understanding is that the eletrical oil pump is for the turbo only, and does not feed the main gallerys . the mains are fed once the engine is started
Correct – on an EMD the prelube pump is just for the turbo.
The more important concern about startup and shutdown than lubrication of the prime mover (except for the turbo) is expansion and contraction of the crankcase, which can lead to coolant leaks around the seals. In the good old days when fuel was cheap it was more economical to leave the engine running to avoid the problems of leaks, the time it took to start the engine and wait for it to come up to operating temperature before putting it under load, and worry about the batteries not having enough oomph to get it started – along with the freezeup, fuel gelling, and oil gelling difficulties. Today the engine designs are much more tolerant of frequent startup and shutdown, and assuming the ambient temperature is not sub-freezing it’s more economical to go through shutdown and startup if the locomotive isn’t going to be needed for 4 or more hours.
RWM
The turbo “soakback” pump is primarily for cooling the turbo bearing after the engine is shut down. There is little load on the turbo bearing on startup, so no real need to pre-lube. Even the main and conrod bearings in the engine, which do have a pretty high load on start up, have enough residual lube so that you don’t need to prelube until you are shut down for roughly a day.
You’re absolutely correct. I could claim faulty memory but I should have just pulled the manual off the shelf and refreshed my memory.
RWM
Alaska, according to recent Trains mag, idles their engines in the 3rd or 4th notch in the severe cold weather to keep them warm enough.
Slightly off topic, but…
Does anyone know why diesel cars and trucks don’t have similar gelling problems? Or how they overcome it?
/Bob
On an ES44 Prelube — is for Main Bearings, Turbo and Power Assemblies.
Another comment: Rail roads are installing Automatic Start Engine Systems which disable auto Stop if Out Side Temperature is below <45 F
Oh they do! But winter blend fuels are used to overcome it, to a point.
The key measurement is cloud point, the temperature at which waxes start to form in the fuel and clog fuel filters. Clouding will generally not occur until ambient temperature is 5-10F belowe the cloud point. #2 diesel has a cloud point between 20F and 40F depending on how it is refined. #1 diesel has a cloud point typically around -40F, which is sufficient for almost the very coldest climates. Even so, many diesel vehicle designs for vehicles that might end up in cold climates have a fuel heater/bypass system so when the vehicle is running, some fuel is heated and recirculated to the fuel tank.
#1 diesel has a lower energy content (95% of #2), is more expensive to refine, and has diminished lubricating qualities compared to #2. Highway diesel during winter months is a blend of #2 and #1 depending upon time of year and climate of the locale; sometimes in northern latitudes straight #1 is marketed side-by-side with winterized blend for those who want it/ Generally a 50-50 blend is good enough for all but the very coldest locales. The danger is filling up a large tank at a low latitude and driving due north.
Here’s more than most want to know:
http://www.exxon.com/USA-English/GFM/Products_Services/Fuels/Diesel_Fuels_FAQ.asp
RWM
[quote user=“chefjavier”]
[quote user=“oltmannd”]
No, you’re very close. There are 3 main worries. One is the coolant freezing. Antifreeze isn’t generally practical in EMD and GE engines because of how likely water leaks are versus the damage caused when antifreeze gets in the lube oil.
The two other reasons are the fuel. Diesel fuel has two critical temps to worry about - the cloud point and the pour point. The cloud point is the temp where parafin (wax) in the fuel crystalizes. You can spec the cloud point to be lower in the winter, but it’ll cost you more for the fuel. The fuel will still flow, but the parafin crystals will clog the fuel filter.
The pour point is the temp the fuel turns to a gel and won’t flow at all. You can spec the pour point, too, but the lower you spec it, the more it costs you. The most common method refiners use to reduce the pour point is blending with #1 fuel oil (kerosene and/or jet fuel).
Even with the engines left idling, keeping the fuel system happy requires some technology. The engines all have fuel pumps that supply a steady flow to the engine with significant return to the tank, even when in notch 8. This flow is warmed by passing thru the injectors (high pressure pump on GEs) before going back to the tank. In very cold climates, this is not enough to keep the fuel in the tank above the cloud point, so most road use fuel preheater which are heat exchangers between the fuel suppy line (upstream of the filters) and the engine cooling system. UP also uses a “hot well” partition in the fuel tank to keep the fuel nea
Interesting. Thanks for your response.
/Bob
About anti freeze in coolant. If these engines dont use it, what stops the engine from rusting on the inside, block etc?
Antifreeze has a corrosion inhibitor!
A corrosion inhibitor is added to the cooling water.
See: http://trains.com/TRC/CS/forums/1125495/ShowPost.aspx
RWM
In extreme cold for 18 wheelers such as -70 (Anything at +10 and below.) your engine is your life and vice versa.
We circulated deisel fuel and a little bit is returned to both tanks, sometimes including tank heaters to fight the man killing cold from turning that fuel to jelly.
I recall several runs across North Dakota during storms at -75 outside with a 50+ miles per hour sustained winds and a cab interior temps of approx 40. The gauges that one night showed all of my temps… trans, axles, engine, reefer everything… at very low values fighting the cold.
Things break that cold.
Sometimes we had the reefer HEAT the perishables like medicines, drugs, paints etc to keep it safe. Crazy huh? Also that reefer trailer and a cellphone is your last bastion of safety should your truck engine fail. Most company trucks didnt have APUs on board. Some lucky ones did.
Fuel is cheap that cold. Run it 24/7.
I also remember running the rig back and forth in it’s final daytime parking spot for my 10 hours off to pack the snow down and keep from getting stuck when it’s time to leave. One other thing, rubber lines between cab and trailers rule in the cold. The plasticy crap breaks at anything below -20 stranding you wherever you might be while turning very tightly.
I was a diesel fitter for many years once but,
that is very interesting and ive learnt something new today, thanks!
I can see why an engine of the size we are talking about, why antifreeze isnt used as the stuff has a searching action. If it gets in the lube oil= big bucks!
I don’t think so. North Dakota has NEVER seen temps as low as -75. The only places in the continental US that could get that low are the valleys around Gunnison Colorado, and the valleys of central Alaska.
Maybe not for you. That wind chill was beyond -75. Anything below -30 is still very cold. I cannot account for variations in altitude in the north but the higher you go the colder it gets.
Here is another tidbit, truck exhausts become visible at about 15 above. I dont know about railroad locomotives other than steam.
http://www.usatoday.com/weather/wcstates.htm
-75 is a little much, but not that far off. With Windchill, it certainly could feel that cold at many points through the mountains.
TO KEEP THE ENGINE BLOCK WARM. iF THE BLOCK COOLS IT WILL CONTRACT AND MAKE IT VERY DIFFICULT TO START. WHEN STARTED, NO SMALL TASK, THE PISTINS, CYLINDERS, RINGS WILL BE SUBJECT TO EXCESSIVE WEAR DO TO THE FACT THAT THE CYLINDERS WILL NOT BE LUBRICATED PROPERLY UNTIL THE LUBRICATING OIL WARMS. THE WEAR INCURRED WILL CAUSE EXCESSIVE REPAIRS THAT CAN BE GREATER THAN THE COST OF THE FUEL
Excessive wear will matter little with a driver or team frozen to death within half a day inside the cab. My rule was to never shut that engine off. It might be 3 weeks 24/7 until I get dispatched to a sunny climate.
Once or twice I was forced to shut engine off below freezing with a cooling system casulty or something that required it to be shut down or it be destroyed. Luckly Ive found a nice mechanic who had a wood stove that I could bunk down near.
Once I aborted a salt lake city delivery and stayed in a trux stop in I-80 near Larimie because the truck refused to operate properly with the faulty water temp sensor. It will be two very expensive dealer visits before the real problem was found and replaced. By then too much revenue was lost because something wasnt fixed right the first time that winter.
I could run around the sunny gulf with the bad water sensor the computer overriden with a paper clip. but in winter you dont take short cuts.
Oh, let’s not forget about the nice East Coast people. They put up signs requring no idling enforced by small town cops. Ive gotten my dispatch to issue hotel tickets paid for free and clear by telling them that they can buy my hotel that night for 50 dollars or be handed a ticket for idling plus whatever else wrong the DOT might find.
I usually got the hotel. Hopefully she will start in the morning. If not? Well, that is going to ruin the schedule now wouldnt it.
Now that I look back and recall that the old air starters; you old ones know the kind. 8 seconds of crank time and maybe you get it to fire properly if you work the throttle right. They usually started if the fuel and engine block is warmed all night no matter how cold it got. Not like the picky cranky onery problematic fussy double problem computer crap.
Gotta love it.